// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/filters/vp9_compressed_header_parser.h"

#include "base/logging.h"

namespace media {

namespace {

    // 6.3.6 Inv recenter noneg syntax, inv_recenter_nonneg().
    int InvRecenterNonneg(int v, int m)
    {
        DCHECK_LE(m, kVp9MaxProb / 2);
        if (v > 2 * m)
            return v;

        if (v & 1)
            return m - ((v + 1) >> 1);
        return m + (v >> 1);
    }

    // 6.3.5 Inv remap prob syntax, inv_remap_prob().
    Vp9Prob InvRemapProb(uint8_t delta_prob, uint8_t prob)
    {
        static uint8_t inv_map_table[kVp9MaxProb] = {
            7, 20, 33, 46, 59, 72, 85, 98, 111, 124, 137, 150, 163, 176,
            189, 202, 215, 228, 241, 254, 1, 2, 3, 4, 5, 6, 8, 9,
            10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 24,
            25, 26, 27, 28, 29, 30, 31, 32, 34, 35, 36, 37, 38, 39,
            40, 41, 42, 43, 44, 45, 47, 48, 49, 50, 51, 52, 53, 54,
            55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69,
            70, 71, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84,
            86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 99, 100,
            101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 112, 113, 114, 115,
            116, 117, 118, 119, 120, 121, 122, 123, 125, 126, 127, 128, 129, 130,
            131, 132, 133, 134, 135, 136, 138, 139, 140, 141, 142, 143, 144, 145,
            146, 147, 148, 149, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160,
            161, 162, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175,
            177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 190, 191,
            192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 203, 204, 205, 206,
            207, 208, 209, 210, 211, 212, 213, 214, 216, 217, 218, 219, 220, 221,
            222, 223, 224, 225, 226, 227, 229, 230, 231, 232, 233, 234, 235, 236,
            237, 238, 239, 240, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251,
            252, 253, 253
        };
        uint8_t m = prob;
        uint8_t v = delta_prob;
        DCHECK_GE(m, 1);
        DCHECK_LE(m, kVp9MaxProb);
        DCHECK_LT(v, arraysize(inv_map_table));
        v = inv_map_table[v];
        m--;
        if ((m << 1) <= kVp9MaxProb) {
            return 1 + InvRecenterNonneg(v, m);
        } else {
            return kVp9MaxProb - InvRecenterNonneg(v, kVp9MaxProb - 1 - m);
        }
    }

} // namespace

Vp9CompressedHeaderParser::Vp9CompressedHeaderParser() { }

// 6.3.1 Tx mode syntax
void Vp9CompressedHeaderParser::ReadTxMode(Vp9FrameHeader* fhdr)
{
    int tx_mode;
    if (fhdr->quant_params.IsLossless()) {
        tx_mode = Vp9CompressedHeader::ONLY_4X4;
    } else {
        tx_mode = reader_.ReadLiteral(2);
        if (tx_mode == Vp9CompressedHeader::ALLOW_32X32)
            tx_mode += reader_.ReadLiteral(1);
    }
    fhdr->compressed_header.tx_mode = static_cast<Vp9CompressedHeader::Vp9TxMode>(tx_mode);
}

// 6.3.4 Decode term subexp syntax
uint8_t Vp9CompressedHeaderParser::DecodeTermSubexp()
{
    if (reader_.ReadLiteral(1) == 0)
        return reader_.ReadLiteral(4);
    if (reader_.ReadLiteral(1) == 0)
        return reader_.ReadLiteral(4) + 16;
    if (reader_.ReadLiteral(1) == 0)
        return reader_.ReadLiteral(5) + 32;
    uint8_t v = reader_.ReadLiteral(7);
    if (v < 65)
        return v + 64;
    return (v << 1) - 1 + reader_.ReadLiteral(1);
}

// 6.3.3 Diff update prob syntax
void Vp9CompressedHeaderParser::DiffUpdateProb(Vp9Prob* prob)
{
    const Vp9Prob kUpdateProb = 252;
    if (reader_.ReadBool(kUpdateProb)) {
        uint8_t delta_prob = DecodeTermSubexp();
        *prob = InvRemapProb(delta_prob, *prob);
    }
}

// Helper function to DiffUpdateProb an array of probs.
template <int N>
void Vp9CompressedHeaderParser::DiffUpdateProbArray(Vp9Prob (&prob_array)[N])
{
    for (auto& x : prob_array) {
        DiffUpdateProb(&x);
    }
}

// 6.3.2 Tx mode probs syntax
void Vp9CompressedHeaderParser::ReadTxModeProbs(
    Vp9FrameContext* frame_context)
{
    for (auto& a : frame_context->tx_probs_8x8) {
        DiffUpdateProbArray(a);
    }
    for (auto& a : frame_context->tx_probs_16x16) {
        DiffUpdateProbArray(a);
    }
    for (auto& a : frame_context->tx_probs_32x32) {
        DiffUpdateProbArray(a);
    }
}

// 6.3.7 Coef probs syntax
void Vp9CompressedHeaderParser::ReadCoefProbs(Vp9FrameHeader* fhdr)
{
    const int tx_mode_to_biggest_tx_size[Vp9CompressedHeader::TX_MODES] = {
        0,
        1,
        2,
        3,
        3,
    };
    const int max_tx_size = tx_mode_to_biggest_tx_size[fhdr->compressed_header.tx_mode];
    for (int tx_size = 0; tx_size <= max_tx_size; tx_size++) {
        if (reader_.ReadLiteral(1) == 0)
            continue;

        for (auto& ai : fhdr->frame_context.coef_probs[tx_size]) {
            for (auto& aj : ai) {
                for (auto& ak : aj) {
                    int max_l = (ak == aj[0]) ? 3 : 6;
                    for (int l = 0; l < max_l; l++) {
                        DiffUpdateProbArray(ak[l]);
                    }
                }
            }
        }
    }
}

// 6.3.8 Skip probs syntax
void Vp9CompressedHeaderParser::ReadSkipProb(Vp9FrameContext* frame_context)
{
    DiffUpdateProbArray(frame_context->skip_prob);
}

// 6.3.9 Inter mode probs syntax
void Vp9CompressedHeaderParser::ReadInterModeProbs(
    Vp9FrameContext* frame_context)
{
    for (auto& a : frame_context->inter_mode_probs)
        DiffUpdateProbArray(a);
}

// 6.3.10 Interp filter probs syntax
void Vp9CompressedHeaderParser::ReadInterpFilterProbs(
    Vp9FrameContext* frame_context)
{
    for (auto& a : frame_context->interp_filter_probs)
        DiffUpdateProbArray(a);
}

// 6.3.11 Intra inter probs syntax
void Vp9CompressedHeaderParser::ReadIsInterProbs(
    Vp9FrameContext* frame_context)
{
    DiffUpdateProbArray(frame_context->is_inter_prob);
}

// 6.3.12 Frame reference mode syntax
void Vp9CompressedHeaderParser::ReadFrameReferenceMode(Vp9FrameHeader* fhdr)
{
    bool compound_reference_allowed = false;
    for (int i = VP9_FRAME_LAST + 1; i < VP9_FRAME_MAX; i++)
        if (fhdr->ref_frame_sign_bias[i] != fhdr->ref_frame_sign_bias[1])
            compound_reference_allowed = true;

    if (compound_reference_allowed && reader_.ReadLiteral(1)) {
        fhdr->compressed_header.reference_mode = reader_.ReadLiteral(1) ? REFERENCE_MODE_SELECT : COMPOUND_REFERENCE;
    } else {
        fhdr->compressed_header.reference_mode = SINGLE_REFERENCE;
    }
}

// 6.3.13 Frame reference mode probs syntax
void Vp9CompressedHeaderParser::ReadFrameReferenceModeProbs(
    Vp9FrameHeader* fhdr)
{
    Vp9FrameContext* frame_context = &fhdr->frame_context;
    if (fhdr->compressed_header.reference_mode == REFERENCE_MODE_SELECT)
        DiffUpdateProbArray(frame_context->comp_mode_prob);

    if (fhdr->compressed_header.reference_mode != COMPOUND_REFERENCE)
        for (auto& a : frame_context->single_ref_prob)
            DiffUpdateProbArray(a);

    if (fhdr->compressed_header.reference_mode != SINGLE_REFERENCE)
        DiffUpdateProbArray(frame_context->comp_ref_prob);
}

// 6.3.14 Y mode probs syntax
void Vp9CompressedHeaderParser::ReadYModeProbs(Vp9FrameContext* frame_context)
{
    for (auto& a : frame_context->y_mode_probs)
        DiffUpdateProbArray(a);
}

// 6.3.15 Partition probs syntax
void Vp9CompressedHeaderParser::ReadPartitionProbs(
    Vp9FrameContext* frame_context)
{
    for (auto& a : frame_context->partition_probs)
        DiffUpdateProbArray(a);
}

// 6.3.16 MV probs syntax
void Vp9CompressedHeaderParser::ReadMvProbs(bool allow_high_precision_mv,
    Vp9FrameContext* frame_context)
{
    UpdateMvProbArray(frame_context->mv_joint_probs);

    for (int i = 0; i < 2; i++) {
        UpdateMvProb(&frame_context->mv_sign_prob[i]);
        UpdateMvProbArray(frame_context->mv_class_probs[i]);
        UpdateMvProb(&frame_context->mv_class0_bit_prob[i]);
        UpdateMvProbArray(frame_context->mv_bits_prob[i]);
    }

    for (int i = 0; i < 2; i++) {
        for (auto& a : frame_context->mv_class0_fr_probs[i])
            UpdateMvProbArray(a);
        UpdateMvProbArray(frame_context->mv_fr_probs[i]);
    }

    if (allow_high_precision_mv) {
        for (int i = 0; i < 2; i++) {
            UpdateMvProb(&frame_context->mv_class0_hp_prob[i]);
            UpdateMvProb(&frame_context->mv_hp_prob[i]);
        }
    }
}

// 6.3.17 Update mv prob syntax
void Vp9CompressedHeaderParser::UpdateMvProb(Vp9Prob* prob)
{
    if (reader_.ReadBool(252))
        *prob = reader_.ReadLiteral(7) << 1 | 1;
}

// Helper function to UpdateMvProb an array of probs.
template <int N>
void Vp9CompressedHeaderParser::UpdateMvProbArray(Vp9Prob (&prob_array)[N])
{
    for (auto& x : prob_array) {
        UpdateMvProb(&x);
    }
}

// 6.3 Compressed header syntax
bool Vp9CompressedHeaderParser::Parse(const uint8_t* stream,
    off_t frame_size,
    Vp9FrameHeader* fhdr)
{
    DVLOG(2) << "Vp9CompressedHeaderParser::Parse";
    if (!reader_.Initialize(stream, frame_size))
        return false;

    ReadTxMode(fhdr);
    if (fhdr->compressed_header.tx_mode == Vp9CompressedHeader::TX_MODE_SELECT)
        ReadTxModeProbs(&fhdr->frame_context);

    ReadCoefProbs(fhdr);
    ReadSkipProb(&fhdr->frame_context);

    if (!fhdr->IsIntra()) {
        ReadInterModeProbs(&fhdr->frame_context);
        if (fhdr->interpolation_filter == SWITCHABLE)
            ReadInterpFilterProbs(&fhdr->frame_context);
        ReadIsInterProbs(&fhdr->frame_context);
        ReadFrameReferenceMode(fhdr);
        ReadFrameReferenceModeProbs(fhdr);
        ReadYModeProbs(&fhdr->frame_context);
        ReadPartitionProbs(&fhdr->frame_context);
        ReadMvProbs(fhdr->allow_high_precision_mv, &fhdr->frame_context);
    }

    if (!reader_.IsValid()) {
        DVLOG(1) << "parser reads beyond the end of buffer";
        return false;
    }
    if (!reader_.ConsumePaddingBits()) {
        DVLOG(1) << "padding bits are not zero";
        return false;
    }
    return true;
}

} // namespace media
